1. Field of the Invention
The present invention relates to a conveyor for transporting goods suspended from hangers
2. Background Art
Such a conveyor system, generally known as a hanging conveyor, as a rule has a main conveyor path and several side paths. The side paths can serve to store specific items or material which have been previously removed from the main conveyor path until they are required for further working or processing, whereupon they are unloaded from the side path and regrouped, or simply transported further and introduced again into the main path. Such a side path is generally known as a storage conveyor.
For this purpose it has been known for a long time to structure the side path with a gradient so that the goods hanging on the hangers can slide down a slide rail under their own weight.
A storage conveyor structured in this manner has the disadvantage, on the one hand, that the obtainable length thereof is greatly dependent on the required gradient, since the latter is limited by the existing height of the room within which the conveyor is set up. On the other hand, the slope of the gradient, particularly in the event that the material being transported is of varying weight, has a great influence on the operability of the storage conveyor. Since both light goods (for instance blouses) and heavy goods (for instance coats) are transported over the same path, a compromise must always be found when determining the gradient so as to assure that even the lightest material to be conveyed will dependably slide down.
In the case of heavy materials, such a compromise gradient then necessarily leads to considerable accumulation of pressure at the storage place, as a result of which the maximum possible storage length must be further limited. Since not only horizontal but also vertical space is necessary for storage, the room utilization ratio is poor when gradient paths are employed.
It is also known to structure the storage conveyor path as a horizontally extending rotating spindle onto which the clothes hangers are loaded by means of their hooks. By the provision of an accumulation device which extends into the direction of transport of the conveyor worm and against which the hanger hooks strike, the material being conveyed is then stored (Federal Republic of Germany Ul-88 08 642).
Due to the high weight load in the accumulation region and the frictional forces produced by the stored hangers which, upon rotation of the spindle, jump over the threads, the spindle becomes hot and expands in the horizontal direction, leading to problems at the interface with the further conveyor path adjoining the storage conveyor.
Since, furthermore, support of the spindle is possible only at its two ends, the maximum possible storage length is limited by the strength of the material of which the spindle is made and the weight of the material to be stored.
In order to overcome differences in height within a conveyor system -- for instance one which runs from one floor to another, or from a working place (sewing machine) situated at a normal working height in the side path, into the main path -- so-called oblique conveyors are used.
Oblique conveyors may also comprise a driven spindle (Federal Republic of Germany A-30 47 282). In such case, the thread spiral must be cut deeper in order to assure the advance and support of the hangers.
In addition to the above-mentioned disadvantages of a spindle there is the complicating factor that, since the drive must be arranged outside the region of transport, it is coupled by a universal joint to the spindle, which is technically rather expensive.
Furthermore the hanger hooks can move over one another at the loading and removal places, which can jam the material being transported.
It is also known from U.S. Pat. No. 4,736,687 to provide an oblique conveyor with a rotating strap having a driver hook (Federal Republic of Germany C-35 31 550). If such an oblique conveyor is to be used for the direct transport of clothes hangers, the structural height of the conveyor is limited by the diameter of curvature of the hook. Particularly when a heavy material is being transported, limitations on operation may then exist.